Gamma-amino-butyric acid (GABA) is a major inhibitory neurotransmitter of the central and peripheral nervous systems and is released into the synapse on nerve stimulation where it can modulate the activity of other neurons. For most neurotransmitters, including GABA, neurotransmission is terminated by the rapid uptake of neurotransmitter via specific, high-affinity transporters located in the presynaptic terminal and/or surrounding glial cells. Kanner, B. I., et al., Critical Review of Biochemistry; CRC press; Boca Raton, Fla., 1987; Vol. 22, pp 1-38.
Compounds which inhibit GABA uptake have been shown to be useful in the treatment of anxiety, epilepsy, muscular and movement disorders and mental and emotional disorders (in U.S. Pat. No. 4,383,999), as well as demonstrating potent anticonvulsant effects (Yunger, L. M., et al., J. Pharm. Exp. Ther. 1985, 110, 418-427).
Presently, GABA uptake inhibitors are not known as having utility as anti-tussive agents.